1. Field of the Invention
The present invention relates to a hydraulic clutch, and more particularly to a hydraulic clutch used in a twin-clutch type transmission.
2. Description of Background Art
A hydraulic clutch is known wherein a twin clutch includes first and second hydraulic clutches each of which exhibits a predetermined engaging force by displacing two pressure plates in the axial direction due to oil pressure supplied from the outside. The hydraulic clutches are coaxially arranged adjacent to each other. See, for example, JP-A-2008-89066.
In the hydraulic clutch described in the above-mentioned JP-A-2008-89066, even when the clutch is disengaged, working oil inside of a disengagement-side oil pressure chamber is supplied between a plurality of clutch plates and a plurality of clutch discs from an oil supply hole formed in a clutch center. Accordingly, an oil supply quantity becomes excessively large when the clutch is disengaged so that a drag torque is increased and a rotational speed of a main shaft is increased thus giving rise to a case where a change hitting sound at the time of shifting becomes large.